JP2016024430A - Positive charging toner, liquid developer, developer, developer cartridge, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive charging toner having excellent positive chargeability.SOLUTION: There is provided a positive charging toner that contains toner particles including at least a binder resin and has a surface modified with polyvinylamines.SELECTED DRAWING: None

Description

  The present invention relates to a positively charged toner, a liquid developer, a developer, a developer cartridge, a process cartridge, and an image forming apparatus.

  A method of visualizing image information through an electrostatic charge image such as electrophotography is currently used in various fields. In electrophotography, a latent image (electrostatic latent image) is formed on an image carrier by a charging and exposure process (latent image forming process), and an electrostatic charge image developing toner (hereinafter simply referred to as “toner”). The electrostatic latent image is developed (development process) with a developer for developing electrostatic images (hereinafter sometimes referred to simply as “developer”), and visualized through a transfer process and a fixing process. The Developers used in the dry development method include a two-component developer composed of a toner and a carrier, and a one-component developer using a magnetic toner or a non-magnetic toner alone.

  On the other hand, the liquid developer used in the wet development system is one in which toner particles are dispersed in an insulating carrier liquid, and a type in which toner particles containing a thermoplastic resin are dispersed in a volatile carrier liquid. A type in which toner particles containing a thermoplastic resin are dispersed in a hardly volatile carrier liquid is known.

  For example, in Patent Document 1, (1) a step of producing a toner by suspension polymerization using an aqueous dispersant in an amount such that the size of emulsion particles produced as a by-product is 0.05 to 2 μm. And (2) removing the dispersant from the toner surface, purifying the emulsion particles so as to have a concentration of 0.01 to 2% by weight based on the toner, and then filtering and vacuum drying. The aqueous dispersant is an inorganic dispersant selected from the group consisting of insoluble calcium salts, etc .; a nonionic polymer dispersant selected from the group consisting of polyoxyethylene alkyl ethers, etc .; polyacrylamide, polyvinylamine, etc. An ionic polymer dispersant selected from the group; and an anionic surfactant selected from the group consisting of fatty acid salts and the like; That is one or more, the production method of the toner is described.

  Patent Document 2 includes a first polymer compound having a proton donor site in the main chain and a second polymer compound having a proton acceptor site in the main chain, and the first polymer compound is A toner binder resin composition selected from the group consisting of polycarboxylic acid, polyvinyl alcohol, polyvinylamine, polyarylamine, and maleic anhydride hydrolyzate is described.

  Patent Document 3 describes a liquid developer containing an insulating liquid and toner particles obtained by modifying the surface of toner base particles having a rosin resin with polyallylamine.

  Patent Document 4 describes a liquid developer containing toner particles obtained by surface-modifying toner base particles composed of a material containing a rosin resin and a polyester resin with polyalkyleneimine.

  Patent Document 5 describes a black toner in which toner base particles containing carbon black as a colorant and a binder resin are surface-modified with polyalkyleneimine.

JP 2007-509360 A JP 2008-096980 A JP 2010-181595 A Japanese Patent No. 5176733 Japanese Patent No. 5115379

  An object of the present invention is to provide a positively charged toner excellent in positive chargeability, a liquid developer containing the positively charged toner, a developer, a developer cartridge using the liquid developer or developer, a process cartridge, and an image forming apparatus. Is to provide.

  The invention according to claim 1 is a positively charged toner containing toner particles containing at least a binder resin and having a surface modified with polyvinylamines.

（１）
（式（１）中、ｘ，ｙはそれぞれ独立して１以上の整数を示す。式（１）におけるアミノ基は酸との塩構造を有していてもよい。） The invention according to claim 2 is the positive charging toner according to claim 1, wherein the polyvinylamine is a polyvinylamine represented by the following general formula (1).

(1)
(In formula (1), x and y each independently represents an integer of 1 or more. The amino group in formula (1) may have a salt structure with an acid.)

  The invention according to claim 3 is the positively charged toner according to claim 1 or 2, wherein the acid value of the binder resin is in the range of 1 mgKOH / g to 30 mgKOH / g.

  The invention according to claim 4 is the method according to any one of claims 1 to 3, wherein the content of the polyvinylamine is in the range of 0.1% by mass or more and 3% by mass or less with respect to the whole toner particles. Toner for positive charging.

  The invention according to claim 5 is a liquid developer comprising the positively charged toner according to any one of claims 1 to 4 and a carrier liquid.

  A sixth aspect of the present invention is a developer containing the positive charging toner according to any one of the first to fourth aspects.

  The invention according to claim 7 is a developer cartridge in which the liquid developer according to claim 5 or the developer according to claim 6 is accommodated.

  The invention according to claim 8 is a process cartridge in which the liquid developer according to claim 5 or the developer according to claim 6 is accommodated.

  According to a ninth aspect of the present invention, in the fifth aspect, the image holding member, latent image forming means for forming a latent image on the surface of the image holding member, and the latent image formed on the surface of the image holding member are provided. And developing means for forming a toner image by developing with the liquid developer according to claim 6 or the transfer means for transferring the toner image formed on the surface of the image carrier onto a recording medium. And a fixing unit for fixing the toner image transferred to the recording medium to the recording medium to form a fixed image.

  According to the first aspect of the present invention, there is provided a positively charged toner that is excellent in positive chargeability as compared with the case where the surface of the toner particles is not surface-modified with polyvinylamines.

  According to the second aspect of the present invention, there is provided a positively charged toner that is more excellent in positive chargeability than the case where the polyvinylamine is other than the polyvinylamine represented by the general formula (1).

  According to the third aspect of the invention, there is provided a positively chargeable toner that is excellent in positive chargeability as compared with the case where the acid value of the binder resin is outside the above range.

  According to the fourth aspect of the present invention, there is provided a positively chargeable toner that is excellent in positive chargeability as compared with the case where the content of the polyvinylamine is outside the above range.

  According to the fifth aspect of the present invention, there is provided a liquid developer excellent in positive chargeability as compared with the case where the surface of the toner particles is not surface-modified with polyvinylamines.

  According to the sixth aspect of the present invention, there is provided a developer excellent in positive chargeability as compared with the case where the surface of the toner particles is not surface-modified with polyvinylamines.

  According to the seventh aspect of the present invention, there is provided a developer cartridge that contains a liquid developer or developer that is excellent in positive chargeability as compared with the case where the surface of the toner particles is not surface-modified with polyvinylamines. Provided.

  According to the invention according to claim 8, there is provided a process cartridge containing a liquid developer or developer that is superior in positive chargeability compared to the case where the surface of the toner particles is not surface-modified with polyvinylamines. Is done.

  According to the ninth aspect of the present invention, there is provided an image forming apparatus using a liquid developer or developer that is excellent in positive chargeability as compared with the case where the surface of toner particles is not surface-modified with polyvinylamines. .

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

<Positive charging toner>
A positively charged toner according to an embodiment of the present invention (hereinafter may be simply referred to as “toner”) contains toner particles containing at least a binder resin and having a surface modified with polyvinylamines. To do. The toner particles may contain other components such as a colorant and a release agent as necessary.

  Common binder resins used in toners are polyester resins and styrene / acrylic resins, but they tend to be negatively charged, and polyester resins with good fixability and color development tend to be negatively charged. It is in. Further, when a polyester resin having a good fixability and a silicone-based carrier liquid are combined as a liquid developer, it is difficult to positively charge.

  The charging mechanism of liquid development is fundamentally different from that of dry toner using frictional charging. The mechanism of positive charging generally used in liquid development is that the toner particles themselves are positively charged by adsorbing protons intentionally present in the carrier liquid to the proton receiving layer on the surface of the toner particles. For this reason, the design of the proton-receiving layer on the toner particle surface is extremely important, and this design determines the performance of the liquid developer. However, a conventional liquid developer is prepared by mixing a melt-kneaded dispersion with a carrier and further adding a dispersant, a charge control agent, etc., and developing the solution with a bead mill or the like. In addition, it is difficult to provide the material, and there are few material types that can be used for the dispersant, the charge control agent, and the like, and the solubility in the carrier liquid is low.

  Commercially available charge control agents for positive charging include nigrosine dyes such as “Bontron N-01”, “Bontron N-04”, “Bontron N-07” (above, manufactured by Orient Chemical Industries), “CHUO”. CCA-3 "(manufactured by Chuo Gosei Co., Ltd.), etc .; triphenylmethane dyes containing tertiary amines as side chains; quaternary ammonium salt compounds such as" Bontron P-51 "(manufactured by Orient Chemical Industries)," TP -415 "(manufactured by Hodogaya Chemical Co., Ltd.), cetyltrimethylammonium bromide," COPYCHARGEPXVP435 "(manufactured by Clariant), etc., the only charge control agents applicable to color are colorless quaternary ammonium salt compounds. Others are colored and can only be applied to black. Further, such a charge control agent for positive charging may exert an effect when applied to a dry toner, but the effect is hardly obtained even when applied to a liquid toner. As a charge control agent for positive charging for liquid toner, amine-based materials such as Solsperse 13940/11200 and Antaron V220 are often added, but there are very few applicable material types and solubility in carrier liquid is also low. Therefore, there are many cases where sufficient positive chargeability cannot be obtained.

  In charge control of toner for liquid developer, amine-based materials such as Solsperse 13940, Solsperse 11200, Antaron V220, Antaron 216 and the like are often added at the time of developing into a developing solution. When oil is used, it is difficult to obtain sufficient chargeability. In the conventional method, the charge control substance is added during melt-kneading or when preparing a developer using a disperser such as a bead mill. In this method, the charge control substance is removed from the toner particle surface. It was easy to release and the charging stability was low.

  The present inventors have found that a dry toner or a liquid developer toner having excellent positive charging characteristics can be realized by modifying the surface of toner particles with polyvinylamines. Polyvinylamines are highly cationic substances. When polyvinylamines are present on the surface of the toner particles, they function as a proton-accepting layer, so that it is considered that the toner particles are easily positively charged. It is considered that when the polyvinylamines are chemically adsorbed on the surface of the toner particles by the acid-base reaction, the possibility that the polyvinylamines are detached from the surface of the toner particles becomes extremely low, and a stable positive chargeability can be obtained. Further, since the surface of the toner particles is coated with polyvinylamines, it is considered that the toner particles are hardly affected by the charge of the binder resin or the colorant. As a result, even when a binder resin such as a polyester resin, which is difficult to be positively charged as a liquid developer, and a silicone-based carrier liquid are combined, positive charging is possible. In addition, since polyvinylamines may be used when producing paper, the presence of polyvinylamines on the surface of the toner particles improves the adhesion to paper. Polyvinylamines are almost colorless and transparent, and may be developed on color toners.

(Polyvinylamines)
Polyvinylamines are polymers containing at least vinylamine as a constituent monomer. Polyvinylamines, for example, after N-vinylformamide is polymerized, ammonia, primary amine, secondary amine or the like is added to the N-vinylformamide polymer, and then alkali metal or alkaline earth metal hydroxide, etc. It can be obtained by basic hydrolysis using

  Polyvinylamines may contain N-vinylformamide, N-vinylphthalimide, N-vinylacetamide and the like as a constituent monomer in addition to vinylamine.

（１） The polyvinylamine is preferably a polyvinylamine represented by the following general formula (1). The polyvinylamine represented by the following general formula (1) is a polymer containing vinylamine and N-vinylformamide as constituent monomers.

(1)

  In the formula (1), x and y each independently represent an integer of 1 or more. Moreover, it is preferable that x and y are each independently an integer of 7000 or less. In the formula (1), the ratio of x and y is, for example, in the range of x: y = 99: 1 to 1:99.

In the formula (1), the amino group (—NH ₂ ) may have a salt structure such as hydrochloride or sulfate.

  The weight average molecular weight of the polyvinylamines is preferably in the range of 1,000 to 300,000, and more preferably in the range of 1,000 to 200,000. If the weight average molecular weight of the polyvinylamine is less than 1000, the desired positive chargeability may not be obtained, and if it exceeds 300000, the fixability may be deteriorated.

  Polyvinylamines are preferably alkaline. If the polyvinylamine is alkaline, an acid-base reaction is likely to occur with the acidic toner particle surface, and chemical adsorption is considered to occur. In this case, the pH when polyvinylamines are dissolved in water is preferably in the range of 8 to 14.

  Commercially available materials may be used as the polyvinylamines. An example of a commercially available polyvinylamine is PVAM-0595B (manufactured by Mitsubishi Rayon Co., Ltd.). Further, PVAM-0570B, KP8040 (manufactured by Mitsubishi Rayon Co., Ltd.), Lupamin 1500/1595/3095/4595/9095 (manufactured by BASF), which are copolymers of vinylamine and N-vinylformamide, are also applicable.

  The content of polyvinylamines is preferably in the range of 0.1% by mass to 3% by mass and more preferably in the range of 0.1% by mass to 2% by mass with respect to the entire toner particles. . When the content of polyvinylamine is less than 0.1% by mass, sufficient positive chargeability cannot be obtained, developability is lowered, and dispersion stability and recyclability are lowered when used as a liquid developer. There is a case. On the other hand, when the content of the polyvinylamine exceeds 3% by mass, the positive chargeability is too strong, so that it becomes difficult for the toner to be transferred from the photoreceptor and the developability may be lowered.

(Binder resin)
The binder resin is not particularly limited, and examples thereof include polyester, polystyrene, styrene-acrylic resins such as styrene-alkyl acrylate copolymer and styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene. -Butadiene copolymer, styrene-maleic anhydride copolymer, polyethylene, polypropylene and the like. Further, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like can be mentioned. Of these, polyester resin and styrene-acrylic resin are preferable, and polyester resin is more preferable from the viewpoint of fixability and the like. As the binder resin, the above resins may be used alone, or two or more kinds of resins may be mixed and used.

  As described above, the binder resin preferably contains a polyester resin as a main component. The polyester resin is synthesized from an acid (polyhydric carboxylic acid) component and an alcohol (polyhydric alcohol) component. In the present embodiment, the “acid-derived constituent component” The component part which was an acid component is pointed out, and the "alcohol-derived component" refers to the component part which was an alcohol component before the synthesis of the polyester resin. The main component means 50 parts by mass or more with respect to 100 parts by mass of the binder resin in the toner particles.

[Acid-derived components]
The acid-derived component is not particularly limited, and aliphatic dicarboxylic acids and aromatic carboxylic acids are preferably used. Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic acid, sebacic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid. 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc. Or lower alkyl esters and acid anhydrides thereof, but are not limited thereto. Examples of the aromatic carboxylic acid include lower alkyl esters and acid anhydrides of aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, and naphthalenedicarboxylic acid. Moreover, alicyclic carboxylic acids, such as cyclohexane dicarboxylic acid, etc. are mentioned. In order to secure better fixing properties, it is preferable to use a trivalent or higher carboxylic acid (trimellitic acid or acid anhydride thereof) together with a dicarboxylic acid in order to form a crosslinked structure or a branched structure. Specific examples of the alkenyl succinic acid include dodecenyl succinic acid, dodecyl succinic acid, stearyl succinic acid, octyl succinic acid, octenyl succinic acid and the like.

[Alcohol-derived components]
The alcohol-derived constituent component is not particularly limited, and examples of the aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,20-eicosanediol and the like can be mentioned. In addition, diethylene glycol, triethylene glycol, neopentyl glycol, glycerin, alicyclic diols such as cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A Aromatic diols such as are used. Further, in order to ensure good fixability, a trihydric or higher polyhydric alcohol (glycerin, trimethylolpropane, pentaerythritol) may be used in combination with the diol in order to take a crosslinked structure or a branched structure.

  The method for producing the polyester resin is not particularly limited, and may be produced by a general polyester polymerization method in which an acid component and an alcohol component are reacted. Examples thereof include direct polycondensation and transesterification. What is necessary is just to produce it properly according to a kind. The molar ratio (acid component / alcohol component) when the acid component reacts with the alcohol component varies depending on the reaction conditions and the like, and cannot be generally stated, but is usually about 1/1.

  The polyester resin may be produced, for example, at a polymerization temperature of 180 ° C. or higher and 230 ° C. or lower, and may be reacted while removing the water and alcohol generated during condensation by reducing the pressure in the reaction system as necessary. . When the monomer is not dissolved or compatible at the reaction temperature, the polymerization reaction may be partially accelerated or delayed, and many uncolored particles may be generated. It may be added and dissolved as a solubilizer. The polycondensation reaction may be carried out while distilling off the solubilizing solvent. If there is a monomer with poor compatibility in the copolymerization reaction, the monomer with poor compatibility is preliminarily condensed with the acid or alcohol to be polycondensed and then polymerized together with the main component. It may be condensed.

  Catalysts that may be used in the production of the polyester resin include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; metals such as zinc, manganese, antimony, titanium, tin, zirconium, and germanium Compound; Phosphorous acid compound, phosphoric acid compound, amine compound and the like. Among these, for example, it is preferable to use a tin-containing catalyst such as tin, tin formate, tin oxalate, tetraphenyltin, dibutyltin dichloride, dibutyltin oxide, and diphenyltin oxide.

  In the present embodiment, a compound having a hydrophilic polar group may be used as long as it is copolymerizable as a resin for an electrostatic charge image developing toner. Specific examples include dicarboxylic acid compounds in which an aromatic ring such as sulfonyl-terephthalic acid sodium salt or 3-sulfonylisophthalic acid sodium salt is directly substituted when the resin used is a polyester.

  The weight average molecular weight Mw of the polyester resin is preferably 5000 or more, and more preferably in the range of 5000 to 50000. When this polyester resin is included, it is excellent in rubbing property. When the weight average molecular weight Mw of the polyester resin is less than 5,000, it may be easily separated in some cases, so that problems derived from the liberated resin (filming, increase in fine powder due to brittleness, deterioration in powder fluidity, etc.) occur. There is a case.

  In the toner according to the exemplary embodiment, the resin other than the polyester resin is not particularly limited. Specifically, styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, acrylic acid acrylic monomers such as n-propyl, butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc. Methacrylic monomers; Ethylene unsaturated acid monomers such as acrylic acid, methacrylic acid and sodium styrenesulfonate; Vinyl nitriles such as acrylonitrile and methacrylonitrile; Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether Tells; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and vinyl isopropenyl ketone; Homopolymers of olefin monomers such as ethylene, propylene, and butadiene; Copolymers combining two or more of these monomers Or a mixture thereof, and further, an epoxy resin, a polyester resin, a polyurethane resin, a polyamide resin, a cellulose resin, a polyether resin, etc., a non-vinyl condensation resin, or a mixture of them with the vinyl resin, these Examples thereof include a graft polymer obtained by polymerizing a vinyl monomer in the coexistence. These resins may be used alone or in combination of two or more.

  The content of the binder resin is, for example, in the range of 65% by mass to 95% by mass with respect to the entire toner particles.

  The acid value of the binder resin is preferably in the range of 1 mgKOH / g to 30 mgKOH / g, and more preferably in the range of 7 mgKOH / g to 20 mgKOH / g. If the acid value of the binder resin is less than 1 mgKOH / g, the particle surface adsorption amount of the polyvinylamines used as the surface modifier may be reduced, so that a desired positive charge amount may not be obtained or phase inversion may occur. When granulating using emulsification, the granulating property may be deteriorated. When the acid value of the binder resin exceeds 30 mgKOH / g, the positive chargeability may be inhibited even when polyvinylamines are adsorbed on the particle surface.

(Other ingredients)
The toner particles according to the exemplary embodiment may contain a colorant and, if necessary, other additives such as a release agent, a charge control agent, silica powder, and a metal oxide. These additives may be added internally by, for example, kneading into a binder resin, or may be added externally by, for example, mixing the particles after obtaining toner particles.

  There is no restriction | limiting in particular as a coloring agent, A well-known pigment is used, A well-known dye may be included as needed. Specifically, the following pigments such as yellow, magenta, cyan, and black (black) are used.

  As yellow pigments, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complex compounds, methine compounds, allylamide compounds and the like are used.

  As magenta pigments, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds, and the like are used.

  Examples of cyan pigments include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like.

  As the black pigment, carbon black, aniline black, acetylene black, iron black and the like are used.

  The content of the colorant is, for example, in the range of 1% by mass to 20% by mass with respect to the entire toner particles.

  The release agent is not particularly limited, and examples thereof include plant waxes such as carnauba wax, wood wax and rice bran wax; animal waxes such as bees wax, insect wax, whale wax and wool wax; minerals such as montan wax and ozokerite. Synthetic waxes, synthetic fatty acid solid ester waxes such as Fischer-Tropsch wax (FT wax) having ester side chains, special fatty acid esters, polyhydric alcohol esters; paraffin wax, polyethylene wax, polypropylene wax, polytetrafluoroethylene wax, polyamide wax And synthetic waxes such as silicone compounds. Only one type of release agent may be used, or two or more types may be used.

  The content of the release agent is, for example, in the range of 0.1% by mass to 15% by mass with respect to the entire toner particles.

  There is no restriction | limiting in particular as a charge control agent, A conventionally well-known charge control agent is used. For example, positively chargeable charge control agents such as nigrosine dyes, fatty acid-modified nigrosine dyes, carboxyl group-containing fatty acid-modified nigrosine dyes, quaternary ammonium salts, amine compounds, amide compounds, imide compounds, organometallic compounds; oxycarboxylic acids And negatively chargeable charge control agents such as metal complexes of azo compounds, metal complex dyes and salicylic acid derivatives. Only one type of charge control agent may be used, or two or more types may be used.

  The metal oxide is not particularly limited, and examples thereof include titanium oxide, aluminum oxide, magnesium oxide, zinc oxide, strontium titanate, barium titanate, magnesium titanate, and calcium titanate. Only one type of metal oxide may be used, or two or more types may be used.

<Method for producing toner particles>
The method for producing the toner particles used in the exemplary embodiment is not particularly limited, and examples thereof include a wet production method such as a kneading and pulverizing method, a liquid emulsification method, and a polymerization method.

  For example, binder resin, and if necessary, colorant, other additives, etc. are put into a mixing device such as a Henschel mixer and mixed, and this mixture is melted with a twin screw extruder, Banbury mixer, roll mill, kneader, etc. After kneading, cooling with a drum flaker, etc., coarsely pulverizing with a pulverizer such as a hammer mill, and further pulverizing with a pulverizer such as a jet mill, followed by classification using an air classifier, etc. can get.

  Also, the binder resin, if necessary, the colorant and other additives were dissolved in a solvent such as ethyl acetate, and emulsified and suspended in water to which a dispersion stabilizer such as calcium carbonate was added, and the solvent was removed. Thereafter, particles obtained by removing the dispersion stabilizer are filtered and dried to obtain an in-liquid emulsified dry toner.

  In addition, a polymerizable monomer, a colorant, and a polymerization initiator (for example, benzoyl peroxide, lauroyl peroxide, isopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichloroylbenzoyl peroxide) that form a binder resin , Methyl ethyl ketone peroxide, etc.) and other additives are added to the aqueous phase under stirring and granulated. After the polymerization reaction, the particles are filtered and dried to obtain a polymerized toner.

  The mixing ratio of each material (binder resin, colorant, other additives, etc.) for obtaining the toner may be set in consideration of required characteristics, low temperature fixability, color, and the like. The obtained toner is pulverized in carrier oil using a known pulverizer such as a ball mill, a bead mill, a high-pressure wet atomizer, etc., thereby obtaining toner particles for the liquid developer of this embodiment.

(Surface modification method)
The surface-modified toner particles according to this embodiment are produced by, for example, a method including a step of forming a polyvinylamine layer covering the toner particle surface by surface-modifying the toner particles with polyvinylamines. Since polyvinylamines are water-soluble polymers, in a wet manufacturing method in which granulation is performed in a liquid, the polyvinylamines may be adsorbed on the toner particle surfaces as they are after washing with water before the drying step. Specifically, the toner particle slurry after washing is adjusted to pH 2 to 5, for example, to make the surface of the toner particle acidic, and then excess acid is washed away with ion-exchanged water or the like. Polyvinylamines are added and chemically adsorbed on the surface of the toner particles by acid-base reaction. Thereafter, unreacted polyvinylamines may be removed by washing with ion exchange water or the like.

Specifically, the surface modification of the toner particles is produced, for example, by the following method.
(1) An acid (about 1N hydrochloric acid or nitric acid) is added to a slurry containing toner particles and water, and the pH is adjusted to about 2 to 5 to return the acid sites on the toner particle surface to the acid as much as possible. (2) Ion-exchanged water (3) After reslurry, add water-soluble polyvinylamines, for example, at a liquid temperature in the range of 20 ° C to 35 ° C. Stir for not less than 30 minutes but not more than 60 minutes (4) Solid-liquid separation is performed by washing with ion-exchanged water or the like, or centrifugation, etc. to remove excess polyvinylamine (for example, conductivity is about 20 μS / cm or less) Until)
(5) After filtration, dry (for example, about 35 ° C., at least about 24 hours, moisture content of 1% or less) and crush.

When a polyester resin having an acid value of about 10 is used as a binder resin for toner particles and granulation is performed using phase inversion emulsification, the filtrate on the surface of the toner particles becomes alkaline because the filtrate after washing is alkaline. It seems that there are many parts where the sites (for example, —COOH group) are neutralized to have a salt structure (for example, —COO ^— Na ⁺ , —COO ^— NH ₄ ⁺ ). Therefore, it is preferable to return the salt structure on the surface of the toner particles to an acid (for example, —COOH group) by performing the step (1) so that polyvinylamines are more easily adsorbed by an acid-base reaction. However, the steps (1) and (2) are not essential and may be omitted when a desired positive charge amount is obtained.

<Characteristics of toner particles>
The volume average particle size of the positive charging toner according to the exemplary embodiment is preferably in the range of 3 μm to 8 μm, more preferably in the range of 3 μm to 7 μm, and the number average particle size is in the range of 2 μm to 7 μm. The range is preferable, and the range of 2 μm to 6 μm is more preferable.

  The volume average particle size and the number average particle size are measured by measuring with a Coulter Multisizer II type (manufactured by Beckman-Coulter) with an aperture diameter of 50 μm. At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds.

<Developer>
In the present embodiment, the dry developer is not particularly limited except that it contains the positively charged toner according to the present embodiment, and may have an appropriate component composition according to the purpose. The developer in this embodiment becomes a one-component developer when a positively charged toner is used alone, and becomes a two-component developer when used in combination with a carrier.

  For example, in the case of using a carrier, the carrier is not particularly limited, and examples thereof include known carriers. For example, resins described in JP-A Nos. 62-39879 and 56-11461 are disclosed. Known carriers such as a coated carrier can be used.

  Specific examples of the carrier include the following resin-coated carriers. Examples of the core particles of the carrier include normal iron powder, ferrite, and magnetite molding, and the volume average particle size is in the range of about 30 μm to 200 μm.

  Examples of the coating resin for the resin-coated carrier include styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, acrylic acid 2 -Α-methylene fatty acid monocarboxylic acids such as ethylhexyl, methyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate; nitrogen-containing acrylics such as dimethylaminoethyl methacrylate; acrylonitrile, methacrylonitrile, etc. Vinyl nitriles; vinyl pyridines such as 2-vinyl pyridine and 4-vinyl pyridine; vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl Homopolymers such as vinyl ketones such as ketones; olefins such as ethylene and propylene; vinyl-based fluorine-containing monomers such as vinylidene fluoride, tetrafluoroethylene and hexafluoroethylene; and copolymers composed of two or more types of monomers Furthermore, silicone resins containing methyl silicone, methyl phenyl silicone, etc., polyesters containing bisphenol, glycol, etc., epoxy resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, polycarbonate resins and the like can be mentioned. These resins may be used alone or in combination of two or more. The coating amount of the coating resin is preferably in the range of about 0.1 to 10 parts by mass and more preferably in the range of 0.5 to 3.0 parts by mass with respect to 100 parts by mass of the core particles. preferable.

  For the production of the carrier, a heating type kneader, a heating type Henschel mixer, a UM mixer or the like may be used. Depending on the amount of the coating resin, a heating type fluidized rolling bed, a heating type kiln or the like may be used.

  The mixing ratio of the positively charged toner of the present embodiment and the carrier in the developer is not particularly limited and may be appropriately selected according to the purpose.

<Liquid developer>
In the present embodiment, the liquid developer is not particularly limited except that it contains the positively charged toner according to the present embodiment and a carrier liquid, and may have an appropriate component composition according to the purpose.

(Carrier liquid)
The carrier liquid is an insulating liquid for dispersing the toner particles and is not particularly limited. For example, the carrier liquid is an aliphatic hydrocarbon solvent mainly containing an aliphatic hydrocarbon such as paraffin oil (in a commercial product, Moresco White MT-30P, Moresco White P40, Moresco White P70 manufactured by Matsumura Oil Co., Ltd. Hydrocarbon solvents such as Exon Chemical Co. Isopar L and Isopar M), naphthenic oils, etc. Exol D80, Exol D110, Exol D130, Nippon Petrochemical's Naphthezol L, Naphthezol M, Naphthezol H, New Naphthezol 160, New Naphthezol 200, New Naphthezol 220, New Naphthezol MS-20P, etc. Contains aromatic compounds such as toluene It may be. Further, silicone oils (silicone solvents) such as dimethyl silicone, methylphenyl silicone, and methyl hydrogen silicone can be used. Of these, silicone oil is preferable from the viewpoint of securing image strength and the like.

  The carrier liquid contained in the liquid developer according to the exemplary embodiment may be only one type or two or more types. When the carrier liquid is used as a mixed system of two or more kinds, for example, a mixed system of paraffinic solvent and vegetable oil, a mixed system of silicone solvent and vegetable oil, or the like can be used.

Examples of the volume resistivity of the carrier liquid include a range of 1.0 × 10 ¹⁰ Ω · cm to 1.0 × 10 ¹⁴ Ω · cm, and 1.0 × 10 ¹⁰ Ω · cm to 1.0 × It may be in a range of 10 ¹³ Ω · cm or less.

  The carrier liquid is made of various auxiliary materials such as dispersants, emulsifiers, surfactants, stabilizers, wetting agents, thickeners, foaming agents, antifoaming agents, coagulants, gelling agents, anti-settling agents, charging agents. It may contain a control agent, an antistatic agent, an anti-aging agent, a softening agent, a plasticizer, a filler, a flavoring agent, an anti-tacking agent, a release agent and the like.

(Method for producing liquid developer)
In the liquid developer according to the exemplary embodiment, the toner particles and the carrier liquid are mixed and pulverized using a dispersing machine such as a ball mill, a sand mill, an attritor, or a bead mill, and the toner particles are mixed in the carrier liquid. Obtained by dispersing. The dispersion of the toner particles in the carrier liquid is not limited to the disperser, and may be dispersed by rotating a special stirring blade at a high speed like a mixer, or by the shearing force of a rotor / stator known as a homogenizer. Alternatively, it may be dispersed by ultrasonic waves.

  The concentration of the toner particles in the carrier liquid should be in the range of 0.5% by mass or more and 40% by mass or less from the viewpoint of controlling the viscosity of the developer appropriately and facilitating the circulation of the developer in the developing machine. Is preferable, and the range of 1% by mass to 30% by mass is more preferable.

  Thereafter, the obtained dispersion liquid may be filtered using, for example, a filter such as a membrane filter having a pore diameter of about 100 μm to remove dust, coarse particles, and the like.

<Developer cartridge, process cartridge, image forming apparatus>
The image forming apparatus according to the present embodiment includes, for example, an image carrier (hereinafter sometimes referred to as “photosensitive member”), a charging unit that charges the surface of the image carrier, and a latent image ( The latent image forming means for forming the electrostatic latent image) and the latent image formed on the surface of the image carrier are developed with the liquid developer or developer according to the present embodiment to form a toner image. Means, a transfer means for transferring the toner image formed on the surface of the image carrier onto the recording medium, and a fixing means for fixing the toner image transferred to the recording medium to the recording medium to form a fixed image. Prepare.

  The image forming method according to the present embodiment includes, for example, a latent image forming step of forming a latent image on the surface of the image carrier and a latent image formed on the surface of the image carrier according to the above embodiment. Development process for developing with liquid developer or developer to form toner image, transfer process for transferring toner image formed on surface of image carrier onto recording medium, and toner image transferred to recording medium Fixing the image on a recording medium to form a fixed image.

  In the image forming apparatus, for example, the part including the developing unit may have a cartridge structure (process cartridge) that is detachable from the main body of the image forming apparatus. The process cartridge is not particularly limited as long as it contains the liquid developer or developer according to the present embodiment. The process cartridge contains, for example, the liquid developer or developer according to the present embodiment, and develops a latent image formed on the image carrier with the liquid developer or developer to form a toner image. And is detachably attached to the image forming apparatus.

  Further, the developer cartridge according to the present embodiment is not particularly limited as long as it contains the liquid developer or developer according to the present embodiment. The developer cartridge includes, for example, a developing unit that stores the liquid developer or developer according to the present embodiment and develops a latent image formed on the image holding member with the liquid developer to form a toner image. It is detachable from the image forming apparatus.

  Hereinafter, an image forming apparatus using a liquid developer in the present embodiment will be described as an example with reference to the drawings. However, the present invention is not limited to this configuration.

  FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present embodiment. The image forming apparatus 100 includes a photosensitive member (image holding member) 10, a charging device (charging unit) 20, an exposure device (latent image forming unit) 12, a developing device (developing unit) 14, and an intermediate transfer member (transfer). Means) 16, a cleaner (cleaning means) 18, and a transfer fixing roller (transfer means, fixing means) 28. The photosensitive member 10 has a cylindrical shape, and a charging device 20, an exposure device 12, a developing device 14, an intermediate transfer member 16, and a cleaner 18 are sequentially provided on the outer periphery of the photosensitive member 10.

  Hereinafter, the operation of the image forming apparatus 100 will be described.

  The charging device 20 charges the surface of the photoconductor 10 to a predetermined potential (charging process), and based on the image signal, the exposure device 12 exposes the charged surface with, for example, a laser beam to form a latent image (static image). Electrostatic latent image) is formed (latent image forming step).

  The developing device 14 includes a developing roller 14a and a developer storage container 14b. The developing roller 14a is provided such that a part thereof is immersed in the liquid developer 24 stored in the developer storage container 14b. The liquid developer 24 includes an insulating carrier liquid and toner particles including a binder resin.

  In the liquid developer 24, the toner particles are dispersed. For example, the liquid developer 24 is further stirred by a stirring member provided in the developer container 14b. Variation in the position of the concentration of is reduced. Thus, the liquid developer 24 with reduced toner particle density variation is supplied to the developing roller 14a rotating in the direction of arrow A in the figure.

  The liquid developer 24 supplied to the developing roller 14a is conveyed to the photoconductor 10 in a state where the liquid supply 24 is limited to a constant supply amount by the regulating member, and at a position where the developing roller 14a and the photoconductor 10 are close (or in contact). It is supplied to the electrostatic latent image. As a result, the electrostatic latent image is visualized to become a toner image 26 (development process).

  The developed toner image 26 is conveyed to the photosensitive member 10 that rotates in the direction of arrow B in the figure, and is transferred to a paper (recording medium) 30. In this embodiment, the photosensitive member 26 is transferred before being transferred to the paper 30. The toner image is temporarily transferred to the intermediate transfer body 16 in order to improve the transfer efficiency to the recording medium including the separation efficiency of the toner image from the toner 10, and to perform fixing simultaneously with the transfer to the recording medium (intermediate transfer step). . At this time, a peripheral speed difference may be provided between the photosensitive member 10 and the intermediate transfer member 16.

  Next, the toner image conveyed in the direction of arrow C by the intermediate transfer body 16 is transferred to the paper 30 and fixed at the position of contact with the transfer and fixing roller 28 (transfer process, fixing process). The transfer fixing roller 28 sandwiches the paper 30 together with the intermediate transfer body 16, and causes the toner image on the intermediate transfer body 16 to adhere to the paper 30. As a result, the toner image is transferred to the paper 30, and the toner image is fixed on the paper to form a fixed image 29. The fixing of the toner image is preferably performed by applying a heating element to the transfer fixing roller 28 and applying pressure and heating. The fixing temperature is usually in the range of 120 ° C. or higher and 200 ° C. or lower.

  If the intermediate transfer member 16 has a roller shape as shown in FIG. 1, it forms a roller pair with the transfer fixing roller 28. Therefore, the intermediate transfer member 16 and the transfer fixing roller 28 conform to the fixing roller and the pressing roller in the fixing device, respectively. It shows a fixing function. That is, when the sheet 30 passes through the nip formed between the intermediate transfer body 16 and the transfer fixing roller 28, the toner image is transferred and heated and pressed against the intermediate transfer body 16 by the transfer fixing roller 28. The As a result, the binder resin in the toner particles constituting the toner image is softened, and the toner image is infiltrated into the fibers of the paper 30 to form a fixed image 29 on the paper 30.

  In this embodiment, fixing is performed simultaneously with the transfer to the paper 30. However, the transfer process and the fixing process may be performed separately, and the fixing may be performed after the transfer. In this case, the transfer roller for transferring the toner image from the photoconductor 10 has a function according to the intermediate transfer body 16.

  On the other hand, in the photoreceptor 10 that has transferred the toner image 26 to the intermediate transfer member 16, the toner particles remaining without being transferred are conveyed to a contact position with the cleaner 18 and collected by the cleaner 18. If the transfer efficiency is close to 100% and residual toner is not a problem, the cleaner 18 may not be provided.

  The image forming apparatus 100 may further include a neutralization device (not shown) that neutralizes the surface of the photoconductor 10 after the transfer and before the next charging.

  For example, the charging device 20, the exposure device 12, the developing device 14, the intermediate transfer member 16, the transfer fixing roller 28, and the cleaner 18 that are provided in the image forming apparatus 100 are all synchronized with the rotational speed of the photosensitive member 10. May be operated.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

[Example 1]
(Preparation of toner particles)
The toner of this embodiment is obtained by the following method. That is, the following resin particle dispersion, colorant dispersion, and release agent dispersion were prepared. Next, while a predetermined amount of these were mixed and stirred, a polymer of an inorganic metal salt was added thereto and ionically neutralized to form aggregates of the above particles to obtain a desired toner particle size. Next, the pH of the system was adjusted from a weakly acidic to a neutral range with an inorganic hydroxide, and then heated to the glass transition temperature or higher of the resin particles for coalescence. After completion of the reaction, desired toner particles were obtained through sufficient washing, solid-liquid separation, and drying processes.

(Synthesis of crystalline polyester resin)
In a flask, 1982 parts by mass of sebacic acid, 1490 parts by mass of ethylene glycol, 59.2 parts by mass of sodium dimethyl 5-sulfonate and 0.8 part by mass of dibutyltin oxide were reacted at 180 ° C. for 5 hours in a nitrogen atmosphere. Subsequently, a condensation reaction was performed at 220 ° C. under reduced pressure. The polymer was sampled on the way, and when the molecular weight reached Mw (weight average molecular weight) = 20000 and Mn (number average molecular weight) = 8500 by gel permeation chromatography (GPC), the reaction was stopped to obtain a crystalline polyester resin. . The dissolution temperature (DSC peak temperature) was 71 ° C. The measurement result of the content of sodium dimethyl 5-phthalate by NMR was 1 mol% (vs. all components).

(Crystalline polyester resin particle dispersion)
Prepare 160 parts by weight of crystalline polyester resin, 233 parts by weight of ethyl acetate, and 0.1 parts by weight of aqueous sodium hydroxide (0.3N), put them in a separable flask and heat at 75 ° C. A resin mixture was prepared by stirring with a motor (manufactured by Shinto Kagaku Co., Ltd.). While further stirring this resin mixture, 373 parts by mass of ion-exchanged water is gradually added, phase inversion emulsification is performed, the temperature is lowered to 40 ° C. at a temperature lowering rate of 10 ° C./min, and the solvent is removed to remove the crystalline polyester resin. A particle dispersion (solid content concentration: 30% by mass) was obtained.

(Synthesis of non-crystalline polyester resin)
In a heat-dried two-necked flask, 200 parts by mass of dimethyl terephthalate, 85 parts by mass of 1,3-butanediol, and 0.3 parts by mass of dibutyltin oxide as a catalyst were added, and the air in the container was reduced by a vacuum operation. Was made into an inert atmosphere with nitrogen gas, and it stirred by mechanical stirring at 180 rpm for 5 hours. Thereafter, the temperature was gradually raised to 230 ° C. under reduced pressure, and the mixture was stirred for 2 hours. When it became viscous, it was air-cooled, the reaction was stopped, and the amorphous polyester resin (the aromatic dicarboxylic acid-derived component) 240 parts by mass of an amorphous polyester resin containing an acid-derived constituent component having a content of 100 constituent mol% and an alcohol-derived constituent component having an aliphatic diol-derived constituent component content of 100 constituent mol%. did.

  As a result of molecular weight measurement (polystyrene conversion) by GPC, the obtained amorphous polyester resin (1) had a weight average molecular weight (Mw) of 9,500 and a number average molecular weight (Mn) of 4,200. Further, when the DSC spectrum of the non-crystalline polyester resin (1) was measured using the above-mentioned differential scanning calorimeter (DSC), no clear peak was shown, and a stepwise endothermic change was observed. The glass transition temperature at the midpoint of the stepwise endothermic change was 55 ° C. The resin acid value was 13 mgKOH / g.

(Non-crystalline polyester resin particle dispersion)
Prepare 160 parts by mass of an amorphous polyester resin (1), 233 parts by mass of ethyl acetate, and 0.1 parts by mass of an aqueous sodium hydroxide solution (0.3N). Put these in a separable flask at 70 ° C. The mixture was heated and stirred with a three-one motor (Shinto Kagaku Co., Ltd.) to prepare a resin mixture. While further stirring this resin mixture, 373 parts by mass of ion-exchanged water is gradually added, phase inversion emulsification is performed, and the temperature is lowered to 40 ° C. at a temperature lowering rate of 1 ° C./min. A particle dispersion (solid content concentration: 30% by mass) was obtained.

(Preparation of colorant dispersion)
Cyan pigment (CI Pigment Blue 15: 3, manufactured by Dainichi Seika) 45 parts by mass Ionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 5 parts by mass Ion-exchanged water 200 parts by mass And a homogenizer (IKA Ultra Tarrax) for 10 minutes to obtain a colorant dispersion having a volume average particle size of 170 nm.

  Further, in the same manner as the method for preparing a cyan pigment dispersion, yellow pigment (CI Pigment Yellow 74, manufactured by Dainichi Seika), magenta pigment (CI Pigment Red 269, manufactured by Dainichi Seika), black pigment (CI pigment black 7, manufactured by Mitsubishi Chemical Corporation) was used to obtain each colorant dispersion.

(Preparation of release agent dispersion)
Alkyl wax FNP0085 (melting temperature 86 ° C, manufactured by Nippon Seiwa Co., Ltd.) 45 parts by weight Cationic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku) 5 parts by weight Ion-exchanged water 200 parts by weight The above is heated to 90 ° C. After sufficiently dispersing with IKA Ultra Turrax T50, it was dispersed with a pressure discharge type gorin homogenizer to obtain a release agent dispersion having a volume average particle size of 200 nm and a solid content of 24.3 mass%.

(Toner preparation)
Crystalline polyester resin particle dispersion 15 parts by weight Amorphous polyester resin particle dispersion 80 parts by weight Colorant dispersion (for each of Y, M, C, K) 18 parts by weight Release agent dispersion 18 parts by weight Was added with ion-exchanged water so as to have a solid content of 16% by mass, and thoroughly mixed and dispersed in a round stainless steel flask with an Ultra Turrax T50. Next, 0.36 parts by mass of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. The flask was heated to 47 ° C. with stirring in an oil bath for heating. After maintaining at 47 ° C. for 60 minutes, 46 parts by mass of the amorphous polyester resin particle dispersion was slowly added thereto. Thereafter, the pH of the system was adjusted to 9.0 with a 0.55 mol / L sodium hydroxide aqueous solution, and then the stainless steel flask was sealed, and heated to 90 ° C. while continuing stirring using a magnetic seal. Hold for 5 hours. When the particle size at this time was measured, the volume average particle size was 2.3 μm, the volume average particle size distribution index GSDv was 1.24, and the number average particle size distribution index GSDp was 1.30. After completion of the treatment, the mixture was cooled, filtered, sufficiently washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. This was further redispersed in 3 L of ion exchange water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes. This was repeated five more times, and when the electrical conductivity of the filtrate reached 9.7 μS / cm, solid-liquid separation was performed using No4A filter paper by Nutsche suction filtration.

(Surface modification of toner particles)
100 parts by mass of the obtained toner particles were added to 900 parts by mass of ion-exchanged water to prepare a slurry (solid content concentration 10% by mass). The slurry was adjusted to pH 4 by adding 1N hydrochloric acid, stirred for 10 minutes, then subjected to solid-liquid separation by centrifugation, and the supernatant was discarded to remove excess acid. Thereafter, 900 parts by mass of ion-exchanged water was added to reslurry, and a 10% by mass aqueous solution of polyvinylamine PVAM-0595B (manufactured by Mitsubishi Rayon Co., Ltd., Mitsubishi Rayon Co., Ltd., aqueous solution having a weight average molecular weight of 100,000, pH 12) was added to the slurry. 10 parts by mass was added and stirred for 60 minutes. Thereafter, solid-liquid separation was performed by centrifugation, the supernatant was discarded, and excess polyvinylamine was removed. Ion exchange water addition, stirring for 10 minutes, and centrifugation were repeated until the electrical conductivity of the cleaning liquid became 20 μS / cm or less. The mixture was filtered using a filter paper (manufactured by Advantech, No. 4A), washed with ion exchange water, dried at 35 ° C. for 24 hours, and crushed to obtain surface modified toner particles.

(Preparation of liquid developer)
100 parts by mass of the surface-modified toner particles obtained above were mixed with 233 parts by mass of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., dimethyl silicone, 20 cs) to obtain a liquid developer having a solid content concentration of 30% by mass.

(Detection of polyvinylamines)
Detection of polyvinylamines in the surface-modified toner particles was performed using an infrared spectrophotometer (FT / IR-4100, manufactured by JASCO Corporation). Polyvinyl amines are absorbed -NH ₂ in the infrared absorption spectrum 3500-3300Cm ^-1, an absorption characteristic around 1640-1550cm ^-1. When the polyvinylamine has a —NHCHO group, the absorption of —CHO has absorption characteristics in the vicinity of 1740-1720 cm ⁻¹ .

  The surface-modified toner particles can be collected from the liquid developer by the following method. The liquid developer is sedimented by centrifugation (3000 rpm × 5 minutes), the supernatant is removed by decantation, and the toner particles are removed. The collected toner particles are washed with alcohols to desorb polyvinylamines on the surface of the toner particles, and the washed liquid is subjected to high-performance liquid chromatography (manufactured by Tosoh Corporation, HLC-8320GPC type). The weight average molecular weight Mw is obtained, the content of polyvinylamines is obtained using an ultraviolet-visible near-infrared spectrophotometer (manufactured by Shimadzu Corporation, UV-1800 type), and a potentiometric titrator (Hiranuma Sangyo Co., Ltd.) is obtained by the method of JIS K0070. The acid value of the binder resin is determined using a COM-1700 model. The acid value of the binder resin was 13 mgKOH / g.

(Evaluation)
[Developability]
Using the image forming apparatus as shown in FIG. 1, a liquid developer layer made of the liquid developer obtained in each example and each comparative example was formed on the developing roller of the image forming apparatus. Next, the surface potential of the developing roller was set to 300 V, the surface potential of the photoconductor was charged almost uniformly at 500 V, the photoconductor was exposed, the charge on the surface of the photoconductor was attenuated, and the surface potential was set to 50 V. The toner particles on the developing roller and the toner particles on the photosensitive member after the liquid developer layer passed between the photosensitive member and the developing roller were collected with a tape. Each tape used for sampling was affixed on a recording paper, and the concentration of each toner particle was measured. After the measurement, the value obtained by dividing the concentration of toner particles collected on the photoreceptor by the sum of the concentration of toner particles collected on the photoreceptor and the concentration of toner particles collected on the developing roller is multiplied by 100. Was determined as development efficiency, and evaluated according to the following five-step criteria. The results are shown in Table 1.
A: Development efficiency is 96% or more and particularly excellent in development efficiency B: Development efficiency is 91% or more and less than 96%, and development efficiency is excellent C: Development efficiency is 85% or more and less than 91%, practically No problem D: Development efficiency is 55% or more and less than 85% and inferior in development efficiency E: Development efficiency is less than 55% and inferior in development efficiency

[Positive charge]
For the liquid developers obtained in each Example and each Comparative Example, the potential difference was measured using a “microscopic laser zeta electrometer” ZC-3000 manufactured by Microtick Nithion, and evaluated according to the following five-stage criteria. did. Measurement is performed by diluting the liquid developer with a diluting solvent, placing it in a 10 mm transparent cell, applying a voltage of 300 V at 9 mm between the electrodes, and simultaneously observing the moving speed of the particles in the cell with a microscope. Was obtained by calculating the zeta potential from the calculated value. The results are shown in Table 1.
A: Potential difference is +100 mV or more (very good)
B: Potential difference is +85 mV or more and less than +100 mV (good)
C: Potential difference is +70 mV or more and less than +85 mV (normal)
D: Potential difference is +50 mV or more and less than +70 mV (somewhat bad)
E: Potential difference is less than +50 mV (very bad)

[Dispersion stability]
10 mL of the liquid developer obtained in each example and each comparative example was placed in a test tube (12 mm in diameter and 120 mm in length), and the sedimented depth after standing for 14 days was measured. According to the following five-stage criteria evaluated. The results are shown in Table 1.
A: Settling depth is 0 mm
B: Sediment depth greater than 0 mm, 2 mm or less C: Sediment depth, greater than 2 mm, 4 mm or less D: Sediment depth, greater than 4 mm, 6 mm or less E: Sediment depth, 6 mm Bigger than

[Recyclability]
Using the liquid developers obtained in each of Examples and Comparative Examples, an image of a predetermined pattern was printed on 50,000 sheets of recording paper (Fuji Xerox Co., Ltd. paper ^{C 2)} formed on. This image formation was performed in a state where supply of the liquid developer from the liquid developer tank of each color to the corresponding stirring device of each color was stopped. After developing an image on 50,000 sheets of recording paper, the liquid development regenerated by diluting the toner particles collected in the stirring device with an insulating liquid so that the solid content is 30% by mass. About the agent (recycled liquid developer), the following method was tested and the adaptability (recyclability) about recycling was evaluated.

Recycled liquid developer 10 mL for each example and each comparative example was placed in a test tube (12 mm in diameter and 120 mm in length), and the sedimentation depth after standing for 10 days was measured and evaluated according to the following five-stage criteria. did. The results are shown in Table 1.
A: Sediment depth is 1 mm or less B: Sediment depth is greater than 1 mm, 3 mm or less C: Sediment depth is greater than 3 mm, 5 mm or less D: Sediment depth is greater than 5 mm, 7 mm E: Depth settling is greater than 7mm

[Example 2]
Surface-modified toner particles and a liquid developer were obtained in the same manner as in Example 1 except that the amount of polyvinylamine PVAM-0595B used was changed to 1 part by mass. The evaluation was made in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]
Surface-modified toner particles and a liquid developer were obtained in the same manner as in Example 1 except that the amount of 10% by mass aqueous solution of polyvinylamine PVAM-0595B was changed to 30 parts by mass. The evaluation was made in the same manner as in Example 1. The results are shown in Table 1.

[Example 4]
Except for changing polyvinylamine to PVAM-0570B (Mitsubishi Rayon Co., Ltd., weight average molecular weight 40000, x: y = 88: 12, pH 9 aqueous solution) which is a copolymer (hydrochloride) of vinylamine and N-vinylformamide. In the same manner as in Example 1, surface modified toner particles and a liquid developer were obtained. The evaluation was made in the same manner as in Example 1. The results are shown in Table 1.

[Example 5]
Surface-modified toner particles and a liquid developer were obtained in the same manner as in Example 1, except that the binder resin of the toner particles was changed to styrene / acrylic resin (Fujikura Kasei Co., Ltd., weight average molecular weight 6500). The evaluation was made in the same manner as in Example 1. The results are shown in Table 1. The acid value of the binder resin was 10 mgKOH / g.

[Example 6]
Surface-modified toner particles and a liquid developer were obtained in the same manner as in Example 1 except that the amount of polyvinylamine PVAM-0595B used was changed to 0.5 parts by mass. The evaluation was made in the same manner as in Example 1. The results are shown in Table 1.

[Example 7]
Surface-modified toner particles and a liquid developer were obtained in the same manner as in Example 1 except that the amount of 10% by mass aqueous solution of polyvinylamine PVAM-0595B was changed to 50 parts by mass. The evaluation was made in the same manner as in Example 1. The results are shown in Table 1.

[Example 8]
Surface-modified toner particles and a liquid developer were obtained in the same manner as in Example 1 except that the amorphous polyester resin was synthesized as follows. In the reaction vessel, 618 parts by mass (11.0 mol) of bisphenol A · PO 2 mol adduct, 162 parts by mass (2.5 mol) of bisphenol A · PO 3 mol adduct, 241 parts by mass of terephthalic acid (9.0 mol) , 13 parts by mass (0.5 mol) of isophthalic acid, 12 parts by mass (0.5 mol) of adipic acid, and 3 parts by mass of titanium diisopropoxybistriethanolamate as a condensation catalyst were added at 230 ° C. under a nitrogen stream. The reaction was carried out for 5 hours while distilling off the generated water, and then the reaction was carried out under reduced pressure of 0.5 kPa or more and 2.5 kPa or less, and the solution was cooled to 175 ° C. when the acid value became 2 mgKOH / g or less. Thereafter, 9 parts by mass (0.3 mol) of trimellitic anhydride was charged, held at 175 ° C. for 1 hour, and then taken out. The obtained resin was cooled to room temperature and then pulverized into particles. The glass transition temperature, weight average molecular weight, and resin acid value were measured in the same manner as in Example 1. The glass transition temperature was 58 ° C., the weight average molecular weight was 4800, and the resin acid value was 1 mgKOH / g. The evaluation was made in the same manner as in Example 1. The results are shown in Table 1.

[Example 9]
Surface-modified toner particles and a liquid developer were obtained in the same manner as in Example 1 except that the amorphous polyester resin was synthesized as follows. In a reaction vessel, 601 parts by mass of ethylene glycol (20.0 mol), 470 parts by mass of dimethyl terephthalate (5.0 mol), 402 parts by mass of isophthalic acid (5.0 mol), and tetra titanate as a condensation catalyst. 3 parts by mass of isopropoxide was added, and the reaction was carried out for 6 hours at 180 ° C. in a nitrogen stream while distilling off the produced methanol. Next, while gradually raising the temperature to 230 ° C., the reaction was performed for 4 hours while distilling off the generated ethylene glycol and water under a nitrogen stream, and the reaction was further performed for 2 hours under a reduced pressure of 0.5 kPa to 2.5 kPa. . The recovered ethylene glycol was 277 parts by mass (9.2 mol). Thereafter, the mixture was cooled to 175 ° C., charged with 43 parts by mass (0.5 mol) of trimellitic anhydride, held at 175 ° C. for 1 hour, and then taken out. The obtained resin was cooled to room temperature and then pulverized into particles. The glass transition temperature, weight average molecular weight, and resin acid value were measured in the same manner as in Example 1. The glass transition temperature was 57 ° C., the weight average molecular weight was 5800, and the resin acid value was 30 mgKOH / g. The evaluation was made in the same manner as in Example 1. The results are shown in Table 1.

[Example 10]
Surface-modified toner particles and a liquid developer were obtained in the same manner as in Example 1 except that the amorphous polyester resin was synthesized as follows. In a reaction vessel, 721 parts by mass (10.4 mol) of bisphenol A · EO 2 mol adduct, 353 parts by mass of terephthalic acid (10.0 mol), and 3 parts by mass of dibutyltin oxide as a condensation catalyst were added, and nitrogen was added at 230 ° C. The reaction was carried out for 10 hours while distilling off the water produced under an air stream, and then the reaction was carried out under a reduced pressure of 0.5 kPa to 2.5 kPa. The obtained resin was cooled to room temperature and then pulverized into particles. The glass transition temperature, weight average molecular weight, and resin acid value were measured in the same manner as in Example 1. The glass transition temperature was 55 ° C., the weight average molecular weight was 5000, and the resin acid value was 0.5 mgKOH / g. The evaluation was made in the same manner as in Example 1. The results are shown in Table 1.

[Example 11]
Surface-modified toner particles and a liquid developer were obtained in the same manner as in Example 1 except that the amorphous polyester resin was synthesized as follows. In the reaction vessel, 599 parts by mass (11.5 mol) of bisphenol A · PO2 mol adduct, 150 parts by mass (2.5 mol) of bisphenol A · PO3 mol adduct, 174 parts by mass of terephthalic acid (7.0 mol) , 25 parts by mass (1.0 mol) of isophthalic acid, 44 parts by mass (2.0 mol) of adipic acid, and 3 parts by mass of tetrabutoxy titanate as a condensation catalyst, and water generated at 230 ° C. under a nitrogen stream The reaction was allowed to proceed for 5 hours while distilling off, followed by reaction under reduced pressure of 0.5 kPa or more and 2.5 kPa or less. When the acid value became 2 mgKOH / g or less, the solution was cooled to 170 ° C. Thereafter, 60 parts by mass (2.1 mol) of trimellitic anhydride was charged, held at 170 ° C. for 1 hour, and then taken out. The obtained resin was cooled to room temperature and then pulverized into particles. The glass transition temperature, weight average molecular weight, and resin acid value were measured in the same manner as in Example 1. The glass transition temperature was 56 ° C., the weight average molecular weight was 4300, and the resin acid value was 35 mgKOH / g. The evaluation was made in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
Toner particles and a liquid developer were obtained in the same manner as in Example 1 except that polyvinylamine was not used. The evaluation was made in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
Instead of polyvinylamine, use 2 parts by weight of quaternary ammonium salt (Orient Chemical Co., Ltd., BONTRON P-51) for yellow, magenta, and cyan pigments, and 1 part by weight for black pigments, and mix with toner particles after drying Except for the above, a liquid developer sample was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Preparation of dry developer)
[Example 12]
10 parts by mass of the surface-modified toner particles obtained in Example 1 were mixed with 190 parts by mass of a positive charging carrier (Japanese Imaging Society standard carrier P-01) to obtain a dry developer.

[Comparative Example 3]
10 parts by mass of the toner particles obtained in Comparative Example 1 were mixed with 190 parts by mass of a positive charging carrier (Japanese Imaging Society Standard Carrier P-01) to obtain a dry developer.

[Comparative Example 4]
10 parts by mass of the surface-modified toner particles obtained in Comparative Example 2 were mixed with 190 parts by mass of a positive charging carrier (Japanese Imaging Society Standard Carrier P-01) to obtain a dry developer.

[Developability of dry developer]
In an environment of 25 ° C. and 50% RH, the developers of Example 12 and Comparative Examples 3 and 4 were changed to a DocuCentreColor400CP remodeling machine manufactured by Fuji Xerox Co., Ltd. ), And 10000 white solid images were output on Fuji Xerox Co., Ltd. A4 paper (J paper), and then a solid batch of 5 cm × 2 cm was developed. A developed toner image was collected using the adhesiveness of the adhesive tape surface, and its mass (W1) was measured. Next, the same developed toner image was transferred to the surface of paper (J paper), and the mass (W2) of the transferred image was measured. From these results, the transfer efficiency was determined by the following formula and evaluated according to the following evaluation criteria. The results are shown in Table 1.
Transfer efficiency (%) = (W2 / W1) × 100

(Development efficiency evaluation criteria)
A: Transfer efficiency is 95% or more B: Transfer efficiency is 87.5% or more and less than 95% C: Transfer efficiency is 80% or more and less than 87.5% D: Transfer efficiency is less than 80%

[Positive charge of dry developer]
The developers of Example 12 and Comparative Examples 3 and 4 are filled in the above-described developing devices, and the amount of charge of the toner that is regulated by the regulating blade of the developing device and conveyed to the photoreceptor is determined by the toner on the developing roller. Was evaluated by analyzing. The charge amount was measured by an E-SPART analyzer manufactured by Hosokawa Micron Corporation. The measurement conditions were a suction flow rate of 0.2 liters / minute, a dust collection air flow rate of 0.6 liters / minute, a blowing nitrogen gas pressure of 0.02 MPa, and the charge amount (Q / m) for each toner was measured. The charge amount distribution was obtained with a toner count of 3000. The results are shown in Table 1.

  The uniformity of the toner charge amount is a value obtained by dividing the maximum frequency charge amount (Q1 / m1) and the measured total toner charge amount by the measurement count (number) in the number distribution of the charge amount per toner. The smaller the absolute value of the difference from Q2 / m2), the more uniform the charge amount distribution, and the larger the absolute value, the more nonuniform.

(Evaluation criteria for charging characteristics)
A: Absolute value of difference is less than 0.8 B: Absolute value of difference is 0.8 or more and less than 1.0 C: Absolute value of difference is 1.0 or more and less than 1.5 D: Absolute value of difference is 1. 5 or more

  Thus, in the Example using the toner particle surface-treated with polyvinylamines, the positive chargeability was excellent as compared with the Comparative Example. Further, in the examples, the developability, dispersion stability, and recyclability were excellent as compared with the comparative examples.

  DESCRIPTION OF SYMBOLS 10 Photosensitive body (image holding body), 12 Exposure apparatus (latent image forming means), 14 Developing apparatus (developing means), 14a Developing roller (developer holding body), 14b Developer accommodating container, 16 Intermediate transfer body (transfer means) ), 18 cleaner (cleaning means), 20 charging device (charging means), 24 liquid developer, 26 toner image, 28 transfer fixing roller (transfer means, fixing means), 29 fixed image, 30 paper (recording medium), 100 Image forming apparatus.

Claims (9)

  A positively charged toner comprising toner particles containing at least a binder resin and having a surface modified with polyvinylamines. The positively charging toner according to claim 1, wherein the polyvinylamine is a polyvinylamine represented by the following general formula (1).

(1)
(In formula (1), x and y each independently represents an integer of 1 or more. The amino group in formula (1) may have a salt structure with an acid.)   The toner for positive charging according to claim 1, wherein an acid value of the binder resin is in a range of 1 mgKOH / g to 30 mgKOH / g.   4. The positive charge according to claim 1, wherein a content of the polyvinylamine is in a range of 0.1% by mass to 3% by mass with respect to the whole toner particles. Toner.   A liquid developer comprising the positive charging toner according to claim 1 and a carrier liquid.   A developer comprising the positive charging toner according to claim 1.   A developer cartridge containing the liquid developer according to claim 5 or the developer according to claim 6.   A process cartridge containing the liquid developer according to claim 5 or the developer according to claim 6. An image carrier,
Latent image forming means for forming a latent image on the surface of the image carrier;
Developing means for developing the latent image formed on the surface of the image carrier with the liquid developer according to claim 5 or the developer according to claim 6 to form a toner image;
Transfer means for transferring the toner image formed on the surface of the image carrier onto a recording medium;
Fixing means for fixing the toner image transferred to the recording medium to the recording medium to form a fixed image;
An image forming apparatus comprising:

Images